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Panorama with Panasonic 20mm f/1.7: vignetting

Discussion in 'Native Lenses' started by sprinke, Jun 4, 2011.

  1. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    I put together this panorama taken with my Pany 20mm. Sadly, it shows some very noticeable vignetting. Is that just something to accept with this lens, and I shouldn't use it for panoramas?

    It's interesting that I had not noticed, nor heard discussed, the vignetting with this lens.

    <a href="http://www.flickr.com/photos/debit72/5795193593/" title="Los Angeles, from Griffith Observatory by debit72, on Flickr"> 5795193593_7eb1fc4f5f_b. "1024" height="182" alt="Los Angeles, from Griffith Observatory"></a>
     
  2. Van

    Van Mu-43 Regular

    32
    Apr 10, 2011
    What f-stop were you shooting at? Vignetting tends to occur the more open a lens is.
     
  3. Hikari

    Hikari Mu-43 All-Pro

    Nov 26, 2010
    Vignetting can be corrected in each image. Also, photomerge in Photoshop can correct for that when the panorama is stitched together.

    What did you use to do this? I think the free Olympus software can make panoramas. I would imagine it would correct for this, but I have not used it.

    Practically every lens will have vignetting to some degree. The shorter the focal length the greater the effect. The are two type of vignetting. Mechanical vignetting where the lens barrel itself blocks the aperture off-axis. This is usually seen at and near the maximum aperture. Then there is natural vignetting which is cause by the cosine fourth law where light striking at an angle will be spead over a greater area causing a loss of exposure. This is very obvious in wide-angle lenses--in flat-plane panoramic cameras a center filter is used to compensate for this. But even at a normal focal length as the 20mm, natural vignetting can be real. The micro lensing on a sensor does not always help in this regard either, but a good lens profile can compensate to a point.
     
  4. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    Totally closed down: f/11.
     
  5. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    Thanks for the info, Hikari.

    I used Canon's Photostitch software. I did try the Photoshop Photomerge, but it looked awful. Perhaps I don't know how to use it properly (and it's an old version - CS2).
     
  6. Pan Korop

    Pan Korop Mu-43 Veteran

    479
    Mar 31, 2011
    Phare Ouest
    Try increasing the overlap--say, to 40%. Using the grid display is helpful, if you don't have a click-stopped panhead.
     
  7. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    Downloaded and tried an open-source program called Hugin. It did an excellent job. Highly recommend!

    <a href="http://www.flickr.com/photos/debit72/5798885922/" title="Griffith Panorama, Take 2 by debit72, on Flickr"> 5798885922_18f26c12ba_b. "1024" height="160" alt="Griffith Panorama, Take 2"></a>
     
    • Like Like x 2
  8. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    A more telephoto lens should help, but if you have Adobe Photoshop CS5 you can also apply Lens Correction to remove the vignetting on each image before you stitch them. Or if you don't have CS5, find out how much vignetting to remove within an inverse mask of a circle with gaussian blur applied in Quick Mask mode, applying the correction in a levels adjustment... then applying to each photo in an action. Lens correction with a saved profile is simpler, if you have that option... but the same thing can be done manually if need be. ;)
     
  9. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Ooh, very nice! :2thumbs:
     
  10. sparkin

    sparkin Mu-43 Regular

    173
    Nov 18, 2010
    Lexington, KY
    Good choice. Had I seen your post earlier I would have recommended Hugin. It is excellent now (I've been using it several years now, even since it was unstable).
     
  11. ~tc~

    ~tc~ Mu-43 Hall of Famer

    Oct 22, 2010
    Houston, TX
    It looks like you were using a polarizer. That could be the cause of the vignetting, it could also be the varying effect of the polarization as the angle to the sun changes. Appears hugin deals with whatever the issue quite nicely
     
  12. Lauzers

    Lauzers Mu-43 Regular

    62
    Jan 6, 2011
    I've got the same problem, but I have to use photoshop to heavily correct those overlapping vignettes.

    5803660029_08d293bd3f_z.
    rialto pan 01 by Lauzers, on Flickr

    I've downloaded Hugin, but no idea how to properly use it?! Sprinke, any tips?
     
    • Like Like x 1
  13. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    I just muddled through ... used the Assistant tab and didn't touch anything else; still came out great.

    Hugin Assistant tab - PanoTools.org Wiki
     
    • Like Like x 1
  14. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    Looks like you found your solution, nice work!

    You mentioned shooting at f/11? I would tend to suggest against that, unless you have a very good reason (need slow shutter speed or absolutely huge DoF) as the lens is sharpest between f/4 and f/5.6, and gets substantially softer above f/8.
     
  15. sprinke

    sprinke Mu-43 All-Pro

    Apr 5, 2011
    Pasadena, CA
    Debi
    It was very bright out ... the shutter speed was 1/4000 already. But thanks for the info.
     
  16. dhazeghi

    dhazeghi Mu-43 Hall of Famer

    Aug 6, 2010
    San Jose, CA
    Dara
    Wow, that's really bright! At ISO 100, a normal sunny day gets me to about f/5.6 1/800. That's 2 1/3 stops brighter!